Dolphins are intelligent marine mammals that inhabit every ocean of the world and are very closely related to whales and porpoises. There are 33 known species of marine dolphins and another 5 species of dolphins that live in rivers. The most commonly known type is the bottlenose dolphin.

My love of these beautiful, sweet and friendly mammals starts from early childhood. A neighbour asked me once while playing with other children in the yard in front of the block what was my favourite animal. You can guess what my answer was. It was then when I was nicknamed "the dolphin".

My interest for these joyful divers continued throughout the years. I have gathered 10 stunning facts about dolphins, some of them really heartbreaking, to share with you.

1. Social Life

Dolphins are very social, living in groups that hunt and play together. Large pods of dolphins can have more than 1000 members. They are highly intelligent and aware of themselves. A dolphin, for example, is able to recognise itself in a mirror. They have strong feelings which would make them help an elder or a weaker member of the pod.

2. The Dolphin Family

Killer whales, pilot whales and false killer whales are not really whales at all, but dolphins. The same applies to the seven species of porpoise. They are part of the dolphin family too. Thus the biggest dolphin is the orca, which is the other name for the killer whale.

3. Lifespan

In the wild dolphins can live for a long time. Orcas may live for 70 years or more. Bottlenose dolphins can live for at least forty years. Dolphins that are kept in captivity die much earlier than those living in the wild.

4. Maternity

Depending on the species, gestation takes nine to seventeen months. After birth, dolphins are particularly maternal. They have been observed nesting and cuddling their young. Similar to women, they go through menopause. Elder feemales take care of the little ones in the pod, once they cannot have calfs of their own.

5. Senses

Dolphins have acute eyesight both in and out of the water. They hear frequencies 10 times the upper limit of adult humans. Their sense of touch is well-developed, though they are reported to have no sense of smell.

6. Breathing

Because dolphins are mammals, they need to come to the surface of the water to breathe. Unlike land mammals that breathe and eat through their mouths, dolphins have separate holes for each task. Dolphins eat through their mouths and breathe through their blowholes. This prevents the dolphin from sucking up water into the lungs when hunting, reducing the risk of drowning.

7. Dolphins' enemy nr. 1

Dolphins have few natural enemies. Surprisingly humans are their main threat. Pollution, fishing and hunting mean some dolphin species have an uncertain future. In 2006, the baiji or Yangtze River dolphin in China was considered officially extinct.

Thousands of dolphins are killed each year for their meat during the annual Taiji and Faroe Islands dolphin hunts. Others are selected to be sold to marine parks. The practice of slaughtering these benevolent intelligent mammals is sadly still called "traditions" by some. There is a great debate undergoing about the necessity of these inhumane practices as dolphin/whale meat and liver are considered to be toxic, thus limited to a maximum of one meal a month for adult men, prohibited in hospitals, forbidden for pregnant and breastfeeding women.

For this year’s hunt in Taiji, which runs from September until March, the Japanese government set a kill quota of 1,940 dolphins of various species, according to the Dolphin Project, which is 120 more than last year. In addition, trainers will be allowed to choose dolphins, pre-sold to marine parks around the world. Many more dolphins are likely injured or killed than what is officially reported. Young dolphins are sometimes released after watching the adult members of their family killed in front of their eyes swimming in the blood of their parents. Their chance of survival of the orphan dolphins is very low.

Humans invade dolphins habitat also by using sailing routes where many mammals get killed or injured by the boats. Military sonar is also highly detrimental to the evolved acoustic organs of the dolphins. The increasing coastal commercial activities are a serious threat to harbour porpoise as they ruin their habitat.

8. Ghost Gear and plastic waste

Many whales and porpoise fall victims to ghost gear (pieces of broken fishing net floating in the oceans) which restrict their movements, cause injuries or the death of the mammals.

According to the World Animal Organisation, "every year more than 100,000 whales, dolphins, seals and turtles get caught in abandoned or lost fishing nets, lines and traps. Made of durable material, this ghost gear can take up to 600 years to break down. Some nets are bigger than football pitches. If these nets float in the ocean they will continue to endanger animals for years to come."

When animals become tangled in ghost gear, they sometimes drown or starve as they try to escape. Others face longer term suffering as they grow and the lines or nets cut into their bodies.

9. Captivity

There are more than 1.000 orcas, dolphins and other members of the dolphin family held in captivity worldwide. Despite their claim, marine parks do not help to conserve marine mammals through their breeding programs as the most commonly bred species kept in captivity are not considered to be threatened or endangered. Captive marine mammals live in small, sterile enclosures and are deprived of their natural activity level, social groups and interactions with their natural environment, and many captive marine mammals develop stereotypic

Captive marine mammals live in small, sterile enclosures and are deprived of their natural activity level, social groups and interactions with their natural environment, and many captive marine mammals develop stereotypic behaviour and/or aggression not known to occur in the wild.

Forcing orcas and dolphins to live in groups dictated by humans disrupts the dynamics of the natural hierarchy, which in turn upsets their natural behaviour.

What we have learned from captive research is that orcas and dolphins are more intelligent than previously imagined, providing more evidence that a life in captivity is inhumane. Despite the critics from animal activists and the general public, aquariums are refraining from returning captive bred animals to the wild as it is still a very profitable industry.

10. Endangered species

Currently, the most endangered species is the vaquita, a species of porpoise, which in Spanish means little cow, is only found in a small area of the northern Gulf of California in Mexico. Its population is estimated to be around only 100 individuals.

The Maui's dolphin is in a dire danger too. It is a subspecies of the world’s smallest dolphin - the Hectors dolphin and is found off the North Island of New Zealand. Its population is currently estimated to be just around 30 individuals living in the wild.

Living in the 21st century, the information era, presents us with the great opportunity to study and enjoy these beautiful mammals without having the need to keep them captive, as well as get informed about bad practices and take initiative to correct them.